My 430 RDM would only cover 4.7 to 5.4. Which is probably why they are been pushed at us !!! New bases and more masts for us to buy !!!???

It is the thickness that makes RDMs masts so strong: to make a SDM as thick as a RDM it would weight a ton.

And in this case the conspiracy theories are quite misplaced: my Hot Sails HotRod 430 is used from my 4.7 Superfreak UL (you could go even smaller if you wanted), and is the recommended mast for my GPS 6.6, a race sail requiring 24cm extension. Quite a range of use: one mast for one of the softest sails around, used in extreme B&J, all the way to a multi-cambered sail. In addition tops and bottoms of the mast line are all exchangeable, so you can buy just the bottom of the next larger mast if you need something longer. Hot Sails and others have whole lines of sails that are designed to be rigged on a single RDM mast, take the Liquid: 5.0 to 7.5 can be rigged on a 430.

How a sail designed for a RDM would work with a SDM, and vice-versa? Who knows, some would work worst, some maybe better, some the same. What's the point?